The asymmetric, heterodonor tridentate ligand 2(S)-amino-4-phosphinobutan-1-ol, S-PNO, has been prepared from (S)-aspartic acid and some aspects of its coordination chemistry with a number of metal complexes investigated. Reaction of S-PNO with appropriate metal precursors led to the isolation of the complexes fac-Cr(CO)(3)(kappa(3)-S-PNO), 1, fac-[Mn(CO)(3)(kappa(3)-S-PNO)]PF(6), 2, and fac-[Re(CO)(3)(kappa(3)-S-PNO)]BF(4), 3. The alcohol and amine donors in fac-Cr(CO)(3)(kappa(3)-S-PNO) were substituted upon addition of trivinylphosphine to 1 to give the complex fac-Cr(CO)(3)(kappa(1)-P-S-PNO) P(C(2)H(3))(3) (2), 4. Addition of base to 4 gave a coordinated linear tridentate P(3) ligand through the formation of two new chelate rings via hydrophosphination of one vinyl group on each coordinated P(C(2)H(3))(3) with the P-H bonds of the complexed S-PNO. The alcohol donor in fac-[Re(CO)(3)(kappa(3)-S-PNO)]BF(4) is labile and can be substituted with tris(2-fluorophenyl) phosphine, PAr(3)(F), to give fac-[Re(CO)(3)(kappa(2)-P,N-S-PNO)(PAr(3)(F))]BF(4), 5. Attempts to form a macrocyclic ligand through addition of base to fac-[Re(CO)(3)(kappa(2)-P,N-S-PNO)(PAr(3)(F))]BF(4) were unsuccessful due to loss of PAr(3)(F) prior to any ring-closure. All the complexes have been fully characterised by spectroscopic and analytical techniques including a single-crystal X-ray structure analysis of 2.
Edwards, P., Newman, P., & Stasch, A. (2011). Coordination chemistry of an asymmetric P,N,O tridentate ligand containing primary phosphine, amine and alcohol donors. Journal of Organometallic Chemistry, 696(8), 1652 - 1658. https://doi.org/10.1016/j.jorganchem.2011.01.031